Well to be honest every time im using topaz i am just playing with my own setting until i find a result i really like.
Dunno what's your photoshop version but atm i am using the cs6 -not the extended one- so everytime i open my topaz a new window will pop up and untill my manual setting there are two more options like.
-You have some defualt settings which are awesome too.I have used them a lot of times.
-You have a preview window too.You can see there your project how it is now and after the furute topaz layer before evn you choose it.Kewl huh?
Have always in your mind this
so you can have a clear opinion what of each one makes and just play with the settings.Either way use a default one and choose
-Either you let it as it is
-or you just edit a bit its settings (of the default one)
In any other case you can always check this source to find more info.
Have always in mind that any questions are welcomed.